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. 1989 Nov;98(3):989–997. doi: 10.1111/j.1476-5381.1989.tb14630.x

Pharmacological characterization of 8-OH-DPAT-induced inhibition of rat hippocampal 5-HT release in vivo as measured by microdialysis.

T Sharp 1, S R Bramwell 1, S Hjorth 1, D G Grahame-Smith 1
PMCID: PMC1854745  PMID: 2574066

Abstract

1. We have previously found that the putative 5-HT1A agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) decreases hippocampal 5-hydroxytryptamine (5-HT) release in the anaesthetized rat, as measured by brain microdialysis. The present study attempted to characterize the receptor involved in this response using a range of monoamine receptor antagonists. 2. The classical 5-HT receptor antagonists, metergoline (5 mg kg-1 s.c.), methysergide (10 mg kg-1 s.c.) and methiothepin (10 mg kg-1 s.c.) each reduced dialysate levels of 5-HT which complicated their use as antagonists in these experiments. Nevertheless, pretreatment with metergoline but not methiothepin and methysergide partially reduced the 5-HT response to a maximally effective dose of 8-OH-DPAT (0.25 mg kg-1 s.c.). 3. The mixed 5-HT 1/beta-adrenoceptor antagonist pindolol (8 mg kg-1 s.c.) was without effect on spontaneous 5-HT output but attenuated the effect of both maximally (0.25 mg kg-1 s.c.) and submaximally (0.05 mg kg-1 s.c.) effective dose of 8-OH-DPAT. In comparison, propranolol (10 mg kg-1 s.c.) did not affect 5-HT output when injected alone and did not alter the response to 8-OH-DPAT (0.25 mg kg-1 s.c.). 4. The 5-HT2 receptor antagonist ritanserin (0.2 mg kg-1 s.c.) and the 5-HT3 receptor antagonist BRL 43694 (0.5 mg kg-1 s.c.) neither altered 5-HT output alone nor significantly changed the response to 8-OH-DPAT (0.25 mg kg-1 s.c.).(ABSTRACT TRUNCATED AT 250 WORDS)

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Selected References

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